The Explosion of Hydrogen and Chlorine. 



The Rate of Explosion of Hydrogen and Chlorine in 

 the dry and in the moist states. By Harold B. 

 Dixon, M.A., F.R.S., Professor of Chemistry; and 

 Mr. J. A. Harker, Dalton Chemical Scholar in the 

 Owens College. 



[Received October 21st, 18 go.) 



This research, a continuation of our previous work on 

 the combination of chlorine and hydrogen, was made with 

 the object of ascertaining whether, in the explosive com- 

 bination of these gases, the action was a direct one, or 

 whether the union was brought about by the interaction of 

 water-vapour present. We have already shown (confirming 

 Pringsheim's statement) that the gases, when thoroughly 

 dried, were not nearly so sensitive to light as when in the 

 moist condition ; about 25 times more light being necessary 

 to explode the dry gas, than that saturated with moisture. 

 The question remained : When once the explosion is started 

 in a portion of the mixed gases (either by light or by a 

 spark), is the propagation of the explosion through the 

 unburnt gases dependent on the presence of water-vapour ? 

 The method employed to solve this problem was the same 

 as that previously used to determine whether the com- 

 bustion of carbonic oxide and of cyanogen by oxygen was 

 effected by the interaction of water-vapour. In the case of 

 carbonic oxide and oxygen the rate of propagation of the 

 combustion is increased by adding water-vapour until it 

 amounts to about 5 per cent of the mixture ; in the case of 



